Johillerit

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Johillerit
Johillerite-553073.jpg
Violet Johillerit the second cinder cone of the volcano Tolbachik , Kamchatka (Far East), Russia (field 4 mm)
General and classification
other names

IMA 1980-014

chemical formula
  • Na (Mg, Zn) 3 Cu (AsO 4 ) 3
  • NaCu (Mg, Zn) 3 [AsO 4 ] 3
  • Cu 2+ NaMg 3 (AsO 4 ) 3
  • NaCuMg 3 (AsO 4 ) 3
Mineral class
(and possibly department) 		Phosphates, arsenates, vanadates
System no. to Strunz
and to Dana 		8.AC.10 ( 8th edition : VII / A.07)
02.38.03.08
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group I 2 / a (No. 15, position 3)Template: room group / 15.3
Lattice parameters a  = 6.7520  Å ; b  = 12.739 Å; c  = 11.068 Å
β  = 100.37 °
Formula units Z  = 4
Physical Properties
Mohs hardness ≈ 3
Density (g / cm 3 ) 4.15 (measured); 4.21 (calculated)
Cleavage very perfect after {010}, good after {100} and {001}
Break ; Tenacity uneven; brittle
colour violet to blue-violet; lavender, violet, blue, bluish gray, brown, pale green, rarely colorless
Line color white to very pale purple
transparency translucent
shine Glass gloss
Crystal optics
Refractive indices n α  = 1.715
n β  = 1.743
n γ  = 1.783
Refractive index n  = 1.747
Birefringence δ = 0.068
Optical character biaxial positive
Axis angle 2V = ≈ 80 ° (measured); 2V = 82 ° (calculated)
Pleochroism strong from X = violet-red through Y = blue-violet to Z = green-blue
Other properties
Chemical behavior soluble in HNO 3 and in HCl

Johillerite is a very rarely occurring mineral from the mineral class of " phosphates , arsenates and vanadates ". It crystallizes in the monoclinic crystal system with the chemical composition NaCuMg 3 (AsO 4 ) 3 and is therefore chemically a sodium - copper - magnesium - arsenate .

At its type locality, Johillerite develops radial aggregates in decomposed tennantite and chalcosine , which are accompanied by konichalcite and copper-containing adamin . The type locality of the mineral is the Tsumeb Mine near Tsumeb , Oshikoto Region , Namibia .

Etymology and history

The discoverer of Johillerite is Wolfgang Bartelke , who showed the strikingly colored mineral to Paul Keller, Professor of Mineralogy and Crystallography at the University of Stuttgart . Keller and his colleagues carried out the investigations necessary for characterization as a new mineral and presented the results to the International Mineralogical Association (IMA), which recognized it in 1980 under the provisional designation IMA 1980-014. In 1982 it was used by a German-American research team led by Paul Keller , Heinz Hess and Pete J. Dunn in the Austrian science magazine "Tschermaks Mineralogical and petrographic messages" as Johillerit ( English Johillerite ) described. The authors named the mineral after the professor of mineralogy at the University of Stuttgart Johannes-Erich Hiller (1911–1972).

The type material for Johillerite (holotype) is available at the University of Stuttgart (location TM-80.14-Tr / 0/824-s27 / 2) and in the National Museum of Natural History , Washington, DC (catalog no. 146969, belonging to the Smithsonian Institution ) Cotype), kept.

In the late 1990s Johillerit was in a fumarole in the Second cinder cone on the north breakthrough of the Great fissure eruption (Great Fissure), volcano Tolbachik , Kamchatka , Far Eastern Federal District , Russia ( Russian Второй шлаковный конус Северного прорыва, Толбачик, Камчатка ), and later also found on two other fumaroles (fumarole "Arsenatnaya", fumarole "Novaya") in this area. In particular, crystallographic and crystal chemical investigations were carried out on this much better crystallized material.

classification

Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , Johillerit belonged to the mineral class of "phosphates, arsenates and vanadates" and there to the division of "anhydrous phosphates [PO 4 ] 3− , without foreign anions", where he formed together with Bradaczekit , Nickenichit , O'Danielit and Yazganit the unnamed group VII / A.07 .

The 9th edition of Strunz's mineral systematics, which has been in effect since 2001 and is used by the IMA, also assigns Johillerit to the class of “phosphates, arsenates and vanadates” and there to the category of “phosphates etc. without additional anions; without H 2 O “. However, this section is even more precisely subdivided according to the size of the cations involved , so that the mineral can be found according to its composition with the cations sodium and magnesium in the sub-section “With medium-sized and large cations”, where it can be found together with Alluaudit , Arseniopleit , Bradaczekit , Groatit (IMA 2008-054), Karyinit , Ferroalluaudit , Ferrohagendorfit , Hagendorfit , Maghagendorfit , Manitobait (IMA 2008-064), Nickenichit, O'Danielit, Varulith and Yazganit the Hagendorfitgruppe with the system number. 8.AC.10 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Johillerit to the class of "phosphates, arsenates and vanadates" and there in the department of "anhydrous phosphates etc.". Here he is in the " Alluaudit subgroup within the Alluaudit-Wyllieit group " with the system no. 38.02.03 and the other members Alluaudit, Ferroalluaudit, Ferrohagendorfit, Groatit, Hagendorfit, Maghagendorfit, Manitobait, Nickenichit, O'Danielit, Varulith and Yazganit within the subdivision of " Anhydrous phosphates etc., (A + B 2+ ) 3 (XO 4 ) 2 “can be found.

Chemism

Microprobe analyzes on Johillerite from the “Tsumeb Mine” showed mean values ​​of 5.4% Na 2 O; 18.3% MgO; 5.4% ZnO; 15.8% CuO and 55.8% As 2 O 3 , from which the empirical formula Na 1.03 Mg 2.70 Zn 0.39 Cu 1.18 As 2.88 O 12 was calculated on the basis of 12 oxygen atoms , which can be idealized to Na (Mg 2.5 Zn 0.5 ) Cu (AsO 4 ) 3 . This ideal formula requires a content of 5.19% Na 2 O in the Johillerite ; 16.88% MgO; 6.82% ZnO; 13.33% CuO and 57.78% As 2 O 3 .

Johillerit is a member of the Alluaudit group, which contains complex sodium metal phosphates and arsenates. The general formula of this group is A (2) A (2) ' A (1) A (1)' A (1) '' M (1) M (2) 2 [ T O 4 ] 3 , the simplified formula becomes given by A (1) A (2) M (1) M (2) 2 [ T O 4 ] 3 .

Johillerite from the fumarole “Arsenatnaya” has an extremely variable chemical composition. There are different varieties with the corresponding empirical formulas:

  • Fe-rich and Cu-depleted: A (2) ′ Na 0.75 ( A (1) ′ Cu 0.85 A (1) Na 0.13 ) M (1) (Mg 0.91 Fe 0.09 ) Σ = 1.00 M (2) (Mg 1.60 Fe 0.34 Cu 0.06 ) Σ = 2.00 (AsO 4 ) 3
  • Fe-rich and Mg-depleted: A (2) ′ Na 0.84 ( A (1) ′ Cu 0.68 A (1) Na 0.33 ) M (1) (Mg 0.68 Zn 0.32 ) Σ = 1.00 M (2) (Mg 0.90 Cu 0.62 Fe 0.32 Al 0.16 ) Σ = 2.00 (AsO 4 ) 3
  • Cu-rich: A (2) ′ Na 0.91 A (1) ′ Cu 0.98 M (1) (Mg 0.74 Cu 0.16 Zn 0.10 ) Σ = 1.00 M (2) ( Mg 1.34 Cu 0.52 Fe 0.14 ) Σ = 2.00 (AsO 4 ) 3

From a general chemical point of view, Johillerite is an arsenate of the alluaudite type with 0.5 <Na <1.5 apfu, 0.5 <Cu A  <1.0 apfu, Ca <0.5 apfu and dominance of Mg over any other M cation .

Johillerite forms continuous mixed crystal rows with Badalovite , Na 2 Mg 2 Fe 3+ (AsO 4 ) 3 , and with Nickenichite, Na (□, Cu) (□, Ca) (Mg, Fe) 3 (AsO 4 ) 3 , as well as an incomplete one Mixed crystal row with Bradaczekit, NaCu 4 (AsO 4 ) 3 . The dominant substitution schemes are: (1) M Mg ↔ M Cu 2+ ; (2) A Cu 2+ + M 2+ ↔ A Na + + M 3+ ; (3) A Na + + M 2+ ↔ A □ 0 + M 3+ and (4) A Cu 2+ + 2M 2+ ↔ A □ 0 + 2M 3+ . The T position is mainly occupied by As 5+ with only minor admixtures of other elements (P, V, S, Si).

Johillerite also represents the Cu 2+ -dominant analogue of the Ca 2+ -dominated Calciojohillerite, with which, however, no solid solution formation was observed.

Crystal structure

Johillerite crystallizes in the monoclinic crystal system in the space group I 2 / a (space group no. 15, position 3) with the lattice parameters a  = 6.7520  Å ; b  = 12.739 Å; c  = 11.068 Å and β = 100.37 ° as well as four formula units per unit cell . The lattice parameters found by Natalia N. Koshlyakova and co-workers on a very copper-rich,  purple-blue johillerite are a = 11.8589  Å ; b  = 12.7283 Å; c  = 6.7702 Å and β = 113.6283 ° ( a and c swapped with respect to the values ​​from Tait & Hawthorne). Template: room group / 15.3

Johillerite crystallizes in the alluaudite structure type. The Alluaudit structure type contains zigzag chains formed by [ M (2) 2 O 10 ] dimers of M (1) O 6 and M (2) O 6 octahedra with common edges, the mutually isolated and distorted M (1 ) O 6 octahedra are connected. T (1) O 4 tetrahedra share all vertices with the M -centered octahedra and thereby form the (010) -layer, whereas every T (2) O 4 tetrahedron has three vertices in common with the M -centered octahedra of a layer. The fourth vertex is a common vertex with the octahedron of the adjacent layer, whereby the layers are connected to a three-dimensional heteropolyhedral framework. The framework contains two types of channels in which the A (1) and A (2) groups of cation positions are located. These groups include six positions: A (1), A (1) ′, and A (1) ′ ′ in the first and A (2), A (2) ′ and A (2) ′ ′ in the second type of channels .

In the crystal structure of the Johillerits sitting in the centers of the planar, square A (1) 'O 4 groups preferably Cu 2+ , in the A (2)' O 8 - polyhedra preferably Na, both in the M (1) O 6 - as well as the M (2) O 6 - octahedra preferably Mg and in the T (1) O 4 - and T (2) O 4 - tetrahedra As 5+ , whereas the other positions have vacancies.

In Johillerite (Ca, Na) is replaced by Cu 2+ as an A group cation. In most of the minerals of the Alluaudite group, the A group cations occur on the A (1) position and are coordinated by seven or eight anions with a mean distance of ≈ 2.5 Å. The question of how a relatively small cation such as Cu 2+ can replace such large cations as Ca and Na in such a large coordination polyhedron is answered as follows: In alluaudit, the A (1) O 7–8 polyhedra share edges with each other and form a chain extending in the direction of the a-axis. In Johillerite the Cu 2+ ions (Ca, Na) do not really replace the center of the A (1) O 7–8 polyhedra, but are found at the common edges between neighboring polyhedra ( A (1) 'position) and basically have a square-planar coordination with two very long apical anions that are not connected to Cu 2+ .

Johillerite is isotypic (isostructural) to Calciojohillerite , Badalovit, Bradaczekit, Nickenichit and other representatives of the Alluaudit group.

properties

morphology

At its type locality in the “Tsumeb Mine”, Johillerite develops radially radiated aggregates, in which, however, individual, thin-tabular {010} and c-axis [001] elongated crystals can be recognized. Their average size is 1.0 × 0.3 × 0.1 mm. The Johillerite of two other finds on the so-called third oxidation zone in the "Tsumeb Mine" show a very similar formation. On the second level found in the “Tsumeb Mine”, however, the Johillerite appears more fibrous than tabular and consequently has a silky sheen.

In contrast, the Johillerite found in fumaroles on the Tolbatschik volcano are much better developed. The active fumarole "Arsenatnaya", discovered in 2012 at the summit of the second cinder cone, contained johillerite as one of the main sublimates. There it forms almost mono-mineral crusts up to 0.5 cm thick on surfaces up to several square decimeters in size. Johillerit is found in perfect, but often only indistinctly formed short to long prismatic crystals up to 5 mm in length. They come together to form bundles, fans and sheaves, as well as radially radial aggregates, which in turn build up the aforementioned crusts. There are also massive, fine-grain incrustations.

physical and chemical properties

The crystals of the Johillerite are violet to blue-violet at the three points of discovery of the type locality, whereas in the fumarole "Arsenatnaya" on Tolbatschik, due to the different chemical composition, they are very variable in color. Purple, violet, blue, bluish-gray, brown, pale green and rarely colorless crystals as well as multicolored formations such as reddish-brown crystals with violet terminations or crystals with colorations from dark gray-blue to light blue were observed. Their streak color is always white to very pale purple. The surfaces of the translucent to transparent crystals have a glass-like, sometimes silk-like sheen , which agrees well with the values ​​for light refraction .  Medium to high values ​​for light refraction (n α = 1.715; n β  = 1.743; n γ  = 1.783) and a high value for birefringence (δ = 0.068) were found on the crystals of Johillerite . Johillerite has a strong pleochroism from X = violet-red through Y = blue-violet to Z = green-blue.

Johillerite has a very perfect cleavability according to {010} and two good cleavages according to {100} and {001}. Due to its brittleness , however , it breaks like amblygonite , with the fracture surfaces being uneven. With a Mohs hardness of ≈ 3, the mineral is one of the medium-hard minerals and, like the reference mineral calcite, can be scratched with a copper coin.

The measured density for Johillerite of the type locality is 4.15 g / cm³, the calculated density 4.21 g / cm³. The calculated densities for Johillerite from the “Arsenatnaya” fumarole on Tolbatschik vary from 4.132 to 4.314 g / cm³ due to their highly variable chemical composition. Johillerit is neither in the long term nor in the short wavelength UV light , a fluorescent .

Johillerit is soluble in nitric acid (HNO 3 ) and hydrochloric acid (HCl).

Education and Locations

Johillerite from the second cinder cone of the Tolbachik volcano, Russia (field of view 3 mm)

So far (as of 2018) Johillerite could only be described as a very rare mineral formation from seven sites from three localities. The type locality is the "Tsumeb Mine" near Tsumeb, Oshikoto region , Namibia , although the exact location within the mine is unknown, but due to the paragenesis and the appearance of the holotype stage, it could come from the E9 pillar of the 31st floor. Two other finds come from the area of ​​the so-called third oxidation zone.

In the second half of the 1990s Johillerit is in a fumarole in the Second ash cone on the north breakthrough of the Great fissure eruption (Great Fissure), volcano Tolbachik ( the volcano Tolbachik coordinates ), Kamchatka , Far Eastern Federal District , Russia has been found. In 2012, Johillerite was found in large quantities in the fumaroles “Arsenatnaya” and “Novaya”, also in the apical part of the second ash cone on Tolbachik.

After all, Johillerite is also known from the slag deposits at the zinc smelter in Genna , Letmathe near Iserlohn , Sauerland , North Rhine-Westphalia , Germany . There are no known occurrences of Johillerite in Austria or Switzerland .

Is Johillerit on its type locality a typical secondary mineral , which is in the oxidation zone an arsenic-rich polymetallic non-ferrous metal - deposit has formed. The zinc comes from the weathering of sphalerite , copper from the weathering of chalcosine and tennantite and the arsenic from the oxidized tennantite. The sodium and magnesium will have been released from the host rock .

In the "Tsumeb Mine" the mineral was first found on a level with corroded copper ores, mainly consisting of tennantite and chalcosine. Paragenesis minerals are green konichalcite and copper-containing adamin . The succession (formation sequence) is indicated with ore → Konichalcit → Adamin → Johillerit. Johillerite from the second find in the third oxidation zone is accompanied by colorless conductivity , white claudetite , yellowish warikahnite , scorodite as well as chalcosine, tennantite and adamin.

Accompanying minerals of johillerite in the fumarole discovered at Tolbatschik in the late 1990s are hematite , tenorite , lammerite , urusovite , orthoclase and bradaczekite. In the fumarole "Arsenatnaya", other representatives of the alluaudite group such as nickenichite, calciojohillerite, badalovite, hatertite , magnesiohatertite and bradaczekite or yurmarinite , hematite, tenorite, tilasite and aphthitalite have been detected in close intergrowth.

use

Due to its rarity, Johillerite is only of interest to mineral collectors.

See also

literature

  • Paul Keller, Heinz Hess, Pete J. Dunn: Johillerit, Na (Mg, Zn) 3 Cu (AsO 4 ) 3 , a new mineral from Tsumeb, Namibia . In: Tschermaks Mineralogische und Petrographische Mitteilungen . tape 29 , 1982, pp. 169–175 ( springer.com [PDF; 572 kB ; accessed on August 9, 2018]).
  • Johillerite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 63 kB ; accessed on August 7, 2018]).

Web links

Commons : Johillerite  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am Paul Keller, Heinz Hess, Pete J. Dunn : Johillerite, Na (Mg, Zn) 3 Cu (AsO 4 ) 3 , a new mineral from Tsumeb, Namibia . In: Tschermaks Mineralogische und Petrographische Mitteilungen . tape 29 , 1982, pp. 169–175 ( springer.com [PDF; 572 kB ; accessed on August 9, 2018]).
  2. ^ Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p.  430 .
  3. ↑ a b c d e f g h Kimberly T. Tait, Frank C. Hawthorne: Johillerite from Tolbachik, Kamchatka Peninsula, Russia: crystal-structure refinement and chemical composition . In: The Canadian Mineralogist . tape 42 , no. 3 , 2004, p. 717–722 , doi : 10.2113 / gscanmin.42.3.717 .
  4. ↑ a b IMA / CNMNC List of Mineral Names; March 2018 (PDF 1.65 MB)
  5. ↑ a b c d e Mindat - Johillerite (English)
  6. ↑ a b c d e f g h i j k l m n o p q Natalia N. Koshlyakova, Natalia V. Zubkova, Igor V. Pekov, Gerald Giester, Evgeny G. Sidorov: Crystal chemistry of Johillerite . In: The Canadian Mineralogist . tape 56 , no. 2 , 2018, p. 189–201 , doi : 10.3749 / canmin.1700075 .
  7. ↑ a b c d Georg Gebhard: Tsumeb II. A Unique Mineral Locality . 1st edition. GG Publishing, Grossenseifen 1991, p. 256-257 .
  8. ^ Georg Gebhard: Tsumeb - a German-African story . 1st edition. Verlag Gebhard-Giesen, Reichshof 1991, p. 1-239 .
  9. ↑ Type mineral catalog Germany - storage of the type material for Johillerit
  10. ↑ Catalog of Type Mineral Specimens - J. (PDF 40 kB) In: docs.wixstatic.com. Commission on Museums (IMA), December 12, 2018, accessed August 29, 2019 .
  11. ↑ Johillerite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 63  kB ; accessed on August 7, 2018]).
  12. ↑ a b SF Glavatskikh, E. Yu. Bykova: The First Find of Exhalative Johillerite, Kamchatka . In: Doklady Akademii Nauk . tape 361 , no. 6 , 1998, pp. 795-798 (Russian).
  13. ↑ a b SF Glavatskikh, E. Yu. Bykova: The First Find of Exhalative Johillerite, Kamchatka . In: Transactions (Doklady) of the Russian Academy of Sciences / Earth Science Section . 361A, no. 6 , 1998, pp. 813-816 (English).
  14. ↑ a b c d Michael Grieser, Karlheinz Groß, Paul Keller: Second find of the rare arsenate mineral Johillerite from Tsumeb . In: Lapis . tape 23 , no. 9 , 1998, pp. 26 .
  15. ↑ Mindat - Number of localities for Johillerit
  16. ↑ a b List of locations for Johillerite in the Mineralienatlas and in Mindat
  17. ↑ Dieter Bender, Wulf Krimmelbein: Current overview: Minerals from the zinc works Genna / Sauerland . In: Mineral World . tape 5 , no. 4 , 1994, pp. 10 .
  18. ^ Igor V. Pekov, Natalia V. Zubkova, Vasiliy O. Yapaskurt, Dmitriy I. Belakovskiy, Inna S. Lykova, Marina F. Vigasina, Evgeny G. Sidorov, Dmitry Yu. Pushcharovsky: New arsenate minerals from the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. I. Yurmarinite, Na 7 (Fe 3+ , Mg, Cu) 4 (AsO 4 ) 6 . In: Mineralogical Magazine . tape 78 , no. 4 , 2014, p. 905-917 , doi : 10.1180 / minmag.2014.078.4.10 .